I'be been doing a lot of tactics and puzzles on this application and others because it was suggested for a new comer to do so. Now I feel like I am comfortable enough in situations that require tactics and thinking to get past. My main problem right now is that I can no longer rely on the basic principles of openings (control centre, develop your pieces, castle etc). So my question to you all is as follows: what is a good, sound opening to study for white and for black? I'd prefer if the openings would help me improve as a player and increase my chess knowledge. It would also be nice if a few books or videos are suggested relating to to the opening.